| Country | Nationality |
| Spain | noun: Spaniard(s) adjective: Spanish |
| Spratly Islands | void |
| Sri Lanka | noun: Sri Lankan(s) adjective: Sri Lankan |
| Sudan | noun: Sudanese (singular and plural) adjective: Sudanese |
| Suriname | noun: Surinamer(s) adjective: Surinamese |
| Svalbard | void |
| Swaziland | noun: Swazi(s) adjective: Swazi |
| Sweden | noun: Swede(s) adjective: Swedish |
| Switzerland | noun: Swiss (singular and plural) adjective: Swiss |
| Syria | noun: Syrian(s) adjective: Syrian |
| Taiwan | noun: Taiwan (singular and plural) note: example - he or she is from Taiwan; they are from Taiwan adjective: Taiwan |
| Tajikistan | noun: Tajikistani(s) adjective: Tajikistani |
| Tanzania | noun: Tanzanian(s) adjective: Tanzanian |
| Thailand | noun: Thai (singular and plural) adjective: Thai |
| Timor-Leste | noun: Timorese adjective: Timorese |
| Togo | noun: Togolese (singular and plural) adjective: Togolese |
| Tokelau | noun: Tokelauan(s) adjective: Tokelauan |
| Tonga | noun: Tongan(s) adjective: Tongan |
| Trinidad and Tobago | noun: Trinidadian(s), Tobagonian(s) adjective: Trinidadian, Tobagonian |
| Tunisia | noun: Tunisian(s) adjective: Tunisian |
| Turkey | noun: Turk(s) adjective: Turkish |
| Turkmenistan | noun: Turkmen(s) adjective: Turkmen |